THE HAGUE, Netherlands — Loved ones of alleged victims of Rodrigo Duterte's "war on drugs" are hoping for "truth and justice" as the former Philippines president faces International Criminal Court charges, their lawyer said on Friday.

The reverberations from Duterte's anti-drugs campaign that killed thousands are still being felt today in the poor communities that bore the brunt, Gilbert Andres told AFP in an interview.

"They want their voices to be heard," said Andres, who represents victims at the ICC and is likely to play a pivotal role in an eventual trial for Duterte.

There is a chance victims would be compensated financially if Duterte were to be convicted for the crime against humanity of murder, "but more importantly, it's really truth and justice," he said.

Duterte, 80, faces ICC charges of 43 murders as a crime against humanity, but Gilbert said this number was just "emblematic" and many more victims and families were expected to come forward.

While Duterte currently faces just one ICC charge, Gilbert revealed that victims are hoping the prosecutor will add more charges to the accusations.

"There were numerous and massive instances of arbitrary detention that occurred side-by-side with the murders of their relatives," said the lawyer.

"There are specific instances of arbitrary detention and the victims hope that it will also be included in the document containing charges," he told AFP.

'Due process'

The lawyer representing Duterte, Nicholas Kaufman, has told AFP in an interview he sees "compelling" reasons for the ICC to throw the case out because it lacks jurisdiction.

Duterte removed the Philippines from the ICC in 2019 and his supporters insist the court therefore has no power over the former president and he should be released.

But Andres said previous jurisprudence from the ICC showed the court did have the jurisdiction in this case.

"I think there's strong case law as well as a statutory basis... for the ICC to still exercise jurisdiction," he said.

He said victims' testimony would show the world the ongoing impact of Duterte's campaign.

"In fact, our position is that it's not really a war on drugs, it's a war against the poor," he said.

"The murdered breadwinners such as the fathers, the brothers, sisters, mothers, actually (this) is still affecting their socio-economic status now."

Duterte backers from around Europe have demonstrated frequently in noisy shows of support for the former president.

Supporters also keep a constant vigil outside the seaside detention centre in The Hague where Duterte is interned.

Andres said it was good they were able to exercise their right to freedom of speech, accusing the man they support of denying human rights to his alleged victims.

"Were the right to life and to due process of the victims of the war on drugs respected by Mr. Duterte? The answer is a resounding no."

The case comes at a key moment for the ICC, under pressure from all sides.

The United States slapped sanctions on the institution after it issued arrest warrants for Israel's Prime Minister Benjamin Netanyahu for alleged war crimes and crimes against humanity in Gaza.

On Thursday, Hungary announced its withdrawal from the ICC as it welcomed Netanyahu, deriding it as a "political court".

But Andres said that the arrest and possible trial of the former president showed the court's importance.

"I think it's very important because what it shows is that international criminal justice is not merely theoretical. It actually is useful and it's being applied right now," said the lawyer.

"It also shows that powerful people can still be subject to accountability no matter how powerful."